As known in the art, a spin valve is a device comprising two or more conducting magnetic materials generally arranged in layers. The electrical resistance through the device changes depending on the relative alignment of magnetism between the magnetic layers. The change in resistance is a result of the magnetoresistance effect.
The layers may be configured so that an external magnetic field can alter the direction of alignment of one (or more) of the layers, while the direction of alignment of the other layer remains constant. In other words, an external magnetic field can change the direction of relative magnetic alignment between the two layers, thus changing the resistance through the device.
In certain applications, a spin valve may operate within an environment that has an external, static magnetic field that can interfere with the spin valve's operation. The external, static field may alter the relative magnetic alignment between the layers causing undesirable changes in resistance.